Preaction System requires activation before water release.

• A. Preaction System
• B. Wet Pipe System
• C. Dry Pipe System
• D. Antifreeze System

Answer: (A)

Preaction systems are designed to minimize accidental water discharge by tying water release to a triggering event. In this type of system, the piping is not charged with water until an activation occurs—typically a detection signal or, in some configurations, a combination of detection and sprinkler actuation. That means water is held back until something detects a hazard, then opens a valve and allows water to fill the pipes and reach the sprinklers.

This contrasts with wet pipe systems, where water is already in the pipes and will discharge immediately when a sprinkler head is activated, and with dry pipe systems that hold air or nitrogen in the pipes and release water into the dry piping only after the sprinkler head is activated. Antifreeze systems are basically wet or dry systems modified with antifreeze solution to prevent freezing, but they don’t define the two-step activation that characterizes a preaction system.

So the statement accurately describes the defining feature of a preaction system: water release requires an activation event first.